Vat dyestuffs of the anthracene series and process of making same



Patented A pr. 23, 1929.

I UNITED STATES.

PATENT OFFICE.

' GEORG KRKNZLEIN AND BALI EBEB'I, OEHOCHST-bN-THE-IAIN, GERMANY, ASSIGN- OBS TO I. G. FARZBENINDUSTRIE AKTIENGESELLSCHAFT, OFFRANKFORT, GERMANY.

YA'J. nxns'rurrs on THE ANTHRACENE seams an rnocnss onmaxmc sum.

No Drawing. Application filed lune 11,1925, Serial No. 36,520, and in Germany August 13, 1924.

' is known that certain vat dyestufis can be produced by fusing di.- or poly-anthrimides obtainable by condensation of a-amh noanthraquinoneswith a-halogenanthraquinoneswith alkaline or acid condensing agents, for instance aluminium chloride. Furthermore it is known that the said vat dyestuffs can be converted into uniform and commercially valuable compounds by subsequently oxidizing them, for instance by means of chromic acid or salts of hypochlorous acid. lhese vat dyestuffs are carbazole derivatives, the most simple type having the following constitution:

E Q. t t

The statement in U. S. Patent No. 1,052,480 that thesedyest-ufis are N-dianthraquinonyL indanthrenes is an error which was corrected in German Patent No. 267,522. (See also Synthesis of Nitrogen Ring Com ounds, Hollins, D. Yen Nostrand (30., New ork, 1924, page .166 1 1 Now we have found that these dyestuffs can be transformed 'into' such of much greater purity by treating them with concentrated sulfuric acid, preferably at an elevated temperature and in presence or absence of boric acid, and then again subjecting them to a suitable oxidation.

This result is of a great-technical value, as it presents anew method for preparing vat dyestufl's yielding dyeings of a particularly great purity. of shade and excellentfastness.

For instance from a-a-dianthrimide by this new process there may be obtained a vat d estufl giving a particularly bright yellow tint of erfect fastness to boiling with a sodium car onate solution.

The following-example illustrates our in then filtered off, washed until neutral and 1 .55

oxidized b means of hypochlorite solution.

After having filtered off the resulting mass 7 and washed it until neutral, the coloring matter is obtained in the form of a deep-yellow, clear paste. It constitutes an excellent vat dyestuflz' which gives considerably purr tint-s with a more reddish hue than the parent product.

We claim;

1. The process of producing vat dyestufis of the anthracene series, consisting in treating with a strong sulfuric acid at a tempera.- ture not exceeding 110 C. the vat dyestuffs obtainable by oxidizing the condensation.

products produced by fusing an a-a-p'olyanthrimide with a condensing agent, precipitat-.

. 'ing the product fromthe sulfuric acid solu-' tion and oxidizing the resulting product.

2. The process of producing vat dyestuffs of the anthracene series, consisting in treat- ,75 ing with a strong sulfuric acid at a temperature not exceeding 110 C. in presence of boric acid the vat dyestuffs obtainable by oxidizing the condensation-products produced by fusing an a-a-polyanthrimide with a condensing agent, precipitating the product from the sulfuric acid solution and oxidizing the resulting product.

3.-As new products, the-vat dyestuffs ob- -tainable'by treating with a strong sulfuric as acid at a temperature not exceeding 110? 'C. the vat dyestuffs obtainable by oxidizing the condensation products produced by fusing an a-a-polya'nthrimide with a. condensing agent, precipitating the product from the sulfuric acid solution and oxidizing the resulting product.

4. As a new product, the vat dyestuif obtainableby treating with astrong sulfuric acid at'a temperature between 75 and C. 05 the vat dyestuff obtainable by oxidizing the condensation product produced by fusing a a-diant-hrimide with a condensing agent, precipitating the product 'from the sulfuric acid solution and oxldizi-ng the resulting product; 1 said dyestufl giving a vat which dyes cotton a yellow tint of a more reddish hue than the tints obtainable b the parent dyestuffs.

In testimony w ereof, we aflix our signatures,

GEOBG KRANZLEIN. RALF EBERT. 

